11beta-hydroxysteroid dehydrogenase activity in human aortic smooth muscle cells.
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11beta-Hydroxysteroid dehydrogenases (11beta-HSD) interconvert cortisol, the physiological glucocorticoid, and its inactive metabolite cortisone in humans. There are two isoforms. The type 1 isoform (11beta-HSD1) catalyzes both 11beta-dehydrogenation (cortisol to cortisone) and the reverse oxoreduction (cortisone to cortisol), but the type 2 isoform (11beta-HSD2) catalyzes only 11beta-dehydrogenation. The diminished dehydrogenase activity has been demonstrated in resistance vessels of genetically hypertensive rats. However, the isoform(s) that plays a significant role in conferring the dehydrogenase activity on vasculature has not been determined. We investigated 11beta-HSD activities in human vascular smooth muscle cells by manipulating 11beta-HSD expressions with antisense oligonucleotides. The results showed that 11beta-HSD2 dominates functioning in the dehydrogenase mode in these cells. This indicates that impairment of 11beta-HSD2 activity in vascular wall may be related to the pathogenesis of hypertension. (+info)
Lack of tissue glucocorticoid reactivation in 11beta -hydroxysteroid dehydrogenase type 1 knockout mice ameliorates age-related learning impairments.
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11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD-1) intracellularly regenerates active corticosterone from circulating inert 11-dehydrocorticosterone (11-DHC) in specific tissues. The hippocampus is a brain structure particularly vulnerable to glucocorticoid neurotoxicity with aging. In intact hippocampal cells in culture, 11beta-HSD-1 acts as a functional 11beta-reductase reactivating inert 11-DHC to corticosterone, thereby potentiating kainate neurotoxicity. We examined the functional significance of 11beta-HSD-1 in the central nervous system by using knockout mice. Aged wild-type mice developed elevated plasma corticosterone levels that correlated with learning deficits in the watermaze. In contrast, despite elevated plasma corticosterone levels throughout life, this glucocorticoid-associated learning deficit was ameliorated in aged 11beta-HSD-1 knockout mice, implicating lower intraneuronal corticosterone levels through lack of 11-DHC reactivation. Indeed, aged knockout mice showed significantly lower hippocampal tissue corticosterone levels than wild-type controls. These findings demonstrate that tissue corticosterone levels do not merely reflect plasma levels and appear to play a more important role in hippocampal functions than circulating blood levels. The data emphasize the crucial importance of local enzymes in determining intracellular glucocorticoid activity. Selective 11beta-HSD-1 inhibitors may protect against hippocampal function decline with age. (+info)
Expression of 11 beta-hydroxysteroid dehydrogenase isozymes and corticosteroid hormone receptors in primary cultures of human trophoblast and placental bed biopsies.
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Interconversion of active and inactive glucocorticoids, e.g. cortisol (F) and cortisone (E) is catalysed by 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) which exists as two isoforms. We have used human placental bed biopsies and an in-vitro cytotrophoblast cell culture system to examine the expression and activity of the 11 beta-HSD isoforms along with that of the glucocorticoid and mineralocorticoid receptors (GR and MR). Immunohistochemistry localized 11 beta-HSD1 to decidualized stromal cells and 11 beta-HSD2 to villous cytotrophoblast, syncytiotrophoblasts and trophoblast cells invading the placental bed and maternal vasculature. In primary cultures of human cytotrophoblast, 11 beta-HSD2, GR and MR mRNA were expressed. Low levels of 11 beta-HSD1 mRNA were noted in these cultured cells, but could be explained on the basis of contaminating, vimentin-positive decidual stromal cells (< or =5%). Enzyme activity studies confirmed the presence of a high-affinity, NAD-dependent dehydrogenase activity (K(m) 137 nmol/l and V(max) 128 pmol E/h/mg protein), indicative of the 11 beta-HSD2 isoform. No reductase activity was observed. The presence of functional MR and GR was determined using Scatchard analyses of dexamethasone and aldosterone binding (MR K(d) 1.4 nmol/l B(max) 3.0; GR K(d) 6.6 nmol/l B(max) 16.2 fmol/ng protein). The expression of 11 beta-HSD1 in maternal decidua and 11 beta-HSD2 in adjacent trophoblast suggests an important role for glucocorticoids in determining trophoblast invasion. The presence of the MR within trophoblast indicates that some of the effects of cortisol could be MR- rather than GR-mediated. (+info)
11 Beta-hydroxysteroid dehydrogenase type 1 is induced in human monocytes upon differentiation to macrophages.
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11beta-hydroxysteroid dehydrogenases (11beta-HSD) perform prereceptor metabolism of glucocorticoids through interconversion of the active glucocorticoid, cortisol, with inactive cortisone. Although the immunosuppressive and anti-inflammatory activities of glucocorticoids are well documented, the expression of 11beta-HSD enzymes in immune cells is not well understood. Here we demonstrate that 11beta-HSD1, which converts cortisone to cortisol, is expressed only upon differentiation of human monocytes to macrophages. 11beta-HSD1 expression is concomitant with the emergence of peroxisome proliferator activating receptor gamma, which was used as a surrogate marker of monocyte differentiation. The type 2 enzyme, 11beta-HSD2, which converts cortisol to cortisone, was not detectable in either monocytes or cultured macrophages. Incubation of monocytes with IL-4 or IL-13 induced 11beta-HSD1 activity by up to 10-fold. IFN-gamma, a known functional antagonist of IL-4 and IL-13, suppressed the induction of 11beta-HSD1 by these cytokines. THP-1 cells, a human macrophage-like cell line, expressed 11beta-HSD1 and low levels of 11beta-HSD2. The expression of 11beta-HSD1 in these cells is up-regulated 4-fold by LPS. In summary, we have shown strong expression of 11beta-HSD1 in cultured human macrophages and THP-1 cells. The presence of the enzyme in these cells suggests that it may play a role in regulating the immune function of these cells. (+info)
Endothelin 1 type a receptor antagonism prevents vascular dysfunction and hypertension induced by 11beta-hydroxysteroid dehydrogenase inhibition: role of nitric oxide.
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BACKGROUND: The enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD) prevents inappropriate activation of the nonselective mineralocorticoid receptors by glucocorticoids. Renal activity of 11beta-HSD is decreased in patients with apparent mineralocorticoid excess (SAME), licorice-induced hypertension, and essential hypertension. Although expressed in vascular cells, the role of 11beta-HSD in the regulation of vascular tone remains to be determined. METHODS AND RESULTS: lycyrrhizic acid (GA; 50 mg/kg IP, twice daily for 7 days) caused a significant inhibition of 11beta-HSD activity and induced hypertension in Wistar-Kyoto rats (157 versus 127 mm Hg in controls; P<0.01). After 11beta-HSD inhibition, aortic endothelial nitric oxide (NO) synthase (eNOS) protein content, nitrate tissue levels, and acetylcholine-induced release of NO were blunted (all P<0.05 versus controls). In contrast, vascular prepro-endothelin (ET)-1 gene expression, ET-1 protein levels, and vascular reactivity to ET-1 were enhanced by GA treatment (P<0.05 versus controls). Chronic ET(A) receptor blockade with LU135252 (50 mg. kg(-1). d(-1)) normalized blood pressure, ET-1 tissue content, vascular reactivity to ET-1, vascular eNOS protein content, and nitrate tissue levels and improved NO-mediated endothelial function in GA-treated rats (P<0.05 to 0.01 versus untreated and verapamil-treated controls). In human endothelial cells, GA increased production of ET-1 in the presence of corticosterone, which indicates that activation of the vascular ET-1 system by 11beta-HSD inhibition can occur independently of changes in blood pressure but is dependent on the presence of glucocorticoids. CONCLUSIONS: Chronic ET(A) receptor blockade normalizes blood pressure, prevents upregulation of vascular ET-1, and improves endothelial dysfunction in 11beta-HSD inhibitor-induced hypertension and may emerge as a novel therapeutic approach in cardiovascular disease associated with reduced 11beta-HSD activity. (+info)
Expression and putative role of 11 beta-hydroxysteroid dehydrogenase isozymes within the human eye.
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PURPOSE: The human eye is an important target tissue for steroid hormones, and glucocorticoids have been implicated in the pathogenesis of ocular disease, including glaucoma. In peripheral tissues, corticosteroid hormone action is regulated at a prereceptor level through the activity of the 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) isozymes: an oxo-reductase (11 beta-HSD1) that activates cortisol (F) from cortisone (E) and a dehydrogenase (11 beta-HSD2) that inactivates F to E. The purpose of this study was to analyze the expression and putative role of 11 beta-HSD within the human eye. METHODS: Immunohistochemical and reverse transcription-polymerase chain reaction (RT-PCR) studies were performed on sections of human ocular tissues, surgical trabecular meshwork (TM) specimens and a ciliary nonpigmented epithelial (NPE) cell-line. Free F and E concentrations in aqueous humor were determined by gas chromatography-mass spectrometry (GC/MS). IOP was measured in eight male volunteers before and after oral ingestion of carbenoxolone (CBX), a known inhibitor of 11 beta-HSD. RESULTS: 11 beta-HSD1 was expressed in the basal cells of the corneal epithelium and the NPE. 11 beta-HSD2 was restricted to the corneal endothelium. RT-PCR revealed mRNA for only the glucocorticoid receptor (GR) in the TM specimens, whereas GR, mineralocorticoid receptor and 11 beta-HSD1 mRNAs were all present in the NPE cell line. The demonstration of free F in excess of E (F/E 14:1) in the aqueous humor suggested predominant 11 beta-HSD1 activity. Compared with baseline (14.7 +/- 1.06 mm Hg, mean +/- SD), the IOP decreased significantly on both the third and seventh days of CBX ingestion (12.48 +/- 1.11 mm Hg, P < 0.0001 and 11.78 +/- 1.50 mm Hg, P < 0.0001, respectively). CONCLUSIONS: These results suggest that the 11 beta-HSD1 isozyme may modulate steroid-regulated sodium transport across the NPE, thereby influencing IOP. (+info)
Improved lipid and lipoprotein profile, hepatic insulin sensitivity, and glucose tolerance in 11beta-hydroxysteroid dehydrogenase type 1 null mice.
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Excess tissue glucocorticoid action may underlie the dyslipidemia, insulin resistance, and impaired glucose tolerance of the metabolic syndrome. 11beta-Hydroxysteroid dehydrogenase type 1 (11beta-HSD-1) catalyzes conversion of circulating inert 11-dehydrocorticosterone into active corticosterone, thus amplifying local intracellular glucocorticoid action, particularly in liver. The importance of 11beta-HSD-1 in glucose homeostasis is suggested by the resistance of 11beta-HSD-1(-/-) mice to hyperglycemia upon stress or obesity, due to attenuated gluconeogenic responses. The present study further investigates the metabolic consequences of 11beta-HSD-1 deficiency, focusing on the lipid and lipoprotein profile. Ad lib fed 11beta-HSD-1(-/-) mice have markedly lower plasma triglyceride levels. This appears to be driven by increased hepatic expression of enzymes of fat catabolism (carnitine palmitoyltransferase-I, acyl-CoA oxidase, and uncoupling protein-2) and their coordinating transcription factor, peroxisome proliferator-activated receptor-alpha (PPARalpha). 11beta-HSD-1(-/-) mice also have increased HDL cholesterol, with elevated liver mRNA and serum levels of apolipoprotein AI. Conversely, liver Aalpha-fibrinogen mRNA levels are decreased. Upon fasting, the normal elevation of peroxisome proliferator-activated receptor-alpha mRNA is lost in 11beta-HSD-1(-/-) mice, consistent with attenuated glucocorticoid induction. Despite this, crucial oxidative responses to fasting are maintained; carnitine palmitoyltransferase-I induction and glucose levels are similar to wild type. Refeeding shows exaggerated induction of genes encoding lipogenic enzymes and a more marked suppression of genes for fat catabolism in 11beta-HSD-1(-/-) mice, implying increased liver insulin sensitivity. Concordant with this, 24-h refed 11beta-HSD-1(-/-) mice have higher triglyceride but lower glucose levels. Further, 11beta-HSD-1(-/-) mice have improved glucose tolerance. These data suggest that 11beta-HSD-1 deficiency produces an improved lipid profile, hepatic insulin sensitization, and a potentially atheroprotective phenotype. (+info)
Reduced activity of 11 beta-hydroxysteroid dehydrogenase in patients with cholestasis.
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Enhanced renal sodium retention and potassium loss in patients with cirrhosis is due to activation of mineralocorticoid receptors (MRs). Increased aldosterone concentrations, however, do not entirely explain the activation of MR in cirrhosis. Here, we hypothesize that cortisol activates MRs in patients with cholestasis. We present evidence that access of cortisol to MRs is a result of bile acid-mediated inhibition of 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta-HSD2), an MR-protecting enzyme that converts cortisol to cortisone. Twelve patients with biliary obstruction and high plasma bile acid levels were studied before and after removal of the obstruction. The urinary ratio of (tetrahydrocortisol + 5 alpha-tetrahydrocortisol)/tetrahydrocortisone, a measure of 11 beta-HSD2 activity, decreased from a median of 1.91 during biliary obstruction to 0.78 at 4 and 8 weeks after removal of the obstruction and normalization of plasma bile acid concentrations. In order to demonstrate that bile acids facilitate access of cortisol to the MR by inhibiting 11 beta-HSD2, an MR translocation assay was performed in HEK-293 cells transfected with human 11 beta-HSD2 and tagged MR. Increasing concentrations of chenodeoxycholic acid led to cortisol-induced nuclear translocation of MR. In conclusion, 11 beta-HSD2 activity is reduced in cholestasis, which results in MR activation by cortisol. (+info)